Cell division

Question 1

What are the two major phase of cell division?

Answer 1

Interphase and mitotic (division) phase

Question 2

What does cell do during interphase?

Answer 2

• DNA is replicated and check for errors in the nucleus
• Protein synthesis occur in the cytoplasm
• Mitochondria grow and divide, increasing in number in the cytoplasm
• Chloroplast grow and divide in plant and algal cell cytoplasm, increasing in number
• The normal metabolic process occur

Question 3

What are the three phase in interphase?

Answer 3

G1, S, G2

Question 4

What does the cell do during the three phase during interphase?

Answer 4

• G1 - the first growth phase - proteins from which organelles are synthesised are produced and organelle replicate. The cell increase in size
• S - Synthesis phase - DNA is replicated in the nucleus
• G2 - the second growth phase - the cell continues to increase in size, energy stores are increased and the duplicated DNA is checked for errors

Question 5

What are the two phase in mitotic phase?

Answer 5

Mitosis and cytokinesis

Question 6

What does the cell do during the two phase in mitotic phase?

Answer 6

• Mitosis - the nucleus divide
• Cytokinesis - the cytoplasm divide and two cells are produced

Question 7

What does checkpoint in cell cycle do?

Answer 7

They monitor and verify whether the processes at each phase of the cell cycle have been accurately completed before the cell is allowed to progress into the next phase

Question 8

Why is mitosis neccesary in organism?

Answer 8

Growth, replacement and repair of tissue in multicellular organism
Asexual reproduction

Question 9

What is the product of mitosis?

Answer 9

Two genetically identical daughter cells

Question 10

What is chromatid?

Answer 10

one of the two identical halves of a chromosome that has been replicated in preparation for cell division

Question 11

What is centromere

Answer 11

The region where two chromatid joined together

Question 12

What is the region where thwo chromatid joined together?

Answer 12

centromere

Question 13

What are the four phases of mitosis?

Answer 13

PMAT
Prophase
Metaphase
Anaphase
Telophase

Question 14

What is a chromosomes?

Answer 14

A single long molecule of DNA

Question 15

What is formed when chromosome is copied?

Answer 15

Sister chromatids are formed and joined at the centromere

Question 16

What happens during Prophase in mitosis?

Answer 16

• The chromosomes coil and condense
• They become visible under light microscope
• The nucleolus disappear and nuclear membrane began to break down
• A pair of centrioles move to either pole of the cell
• Proteins began to form spindle fibres which attach to each centromere of each chromosome
• The spindle fibres start to move the chromosomes to the centre of the cell

Question 17

What happens during Metaphase in mitosis?

Answer 17

The chromosomes are moved by the spindle fibres and lined up at the equator of the cell

Question 18

What happens during Anaphase in mitosis?

Answer 18

The centromeres divide into two and the spindle fibres begin to shorten
This pull the sister chromatids towards opposite poles of the cell

Question 19

What happens during Telophase in mitosis?

Answer 19

The chromids have reached the poles and are now called chromosomes
The spindle apparatus breaks down
The nuclear envelope reforms
The chromosomes uncoil back into their chromatin state
The nucleolus reappears

Question 20

What happens during Cytokinesis in mitosis in animal cells?

Answer 20

A cleavage furrow form around the middle of the cell
The cell surface membrane get pulled inward but cytoskeleton until it is close enough to fuse together, forming two cells

Question 21

What happens during Cytokinesis in mitosis in plant cells?

Answer 21

Vesicles from golgi apparatus begins to assemble in the same place as where the metaphase plant was formed
The vesicles fuse with each other and the cell surface membrance, dividing the cell into two
New section of cell wall then form along the new sections of membrane

Question 22

What is a diploid cell?

Answer 22

A diploid cell is a cell that contains two complete sets of chromosomes

Question 23

What is a haploid cell?

Answer 23

Haploid cells contain one complete set of chromosomes

Question 24

What is gamete?

Answer 24

sex cell

Question 25

What is zygote?

Answer 25

Fertilised egg

Question 26

What is reduction division?

Answer 26

the chromosome number is halved to form haploid cells

Question 27

What is homologous chromosomes?

Answer 27

Matching sets of chromosomes

Question 28

What is alleles?

Answer 28

Different versions of the same genes

Question 29

Describe the process in prophase 1 during meiosis

Answer 29

* Chromosomes soil and condense * Nuclear envelope disintergrates * Nucleolus disappearna and spindle formation begins * The homologous chromosomes pair up, forming bivalents * The chromatids entangle * Causing crossing over

Question 30

Describe the process in metaphase 1 during meiosis

Answer 30

* Homologous pairs of chromosomes line up at the equator * The orientation of each homologous pair on the equator is random and independent of any other homologous pair * This is called indepedent assortment, and can result in many different combination of alleles facing the poles. * This results in genetic variation

Question 31

Describe the process in anaphase 1 during meiosis

Answer 31

* The homologous chromosomes are pulled to the opposite poles and the chromatids stay joined to each other * Entangled chromosomes break off and rejoin, resulting an exchange of DNA * The points at which the chromatids break off and rejoin are called chiasmata * This form recombinant chromatids * The genes being exchange may different alleles of the same gene, meaning the combination of alleles on the recombinant will be diffeent from the allele combination on either the original chromatids * Genetic variation arises from this new combinations of alleles

Question 32

Describe the process in telophase 1 during meiosis

Answer 32

* The chromosomes resemble at each pole * Nuclear envelope reform * Chromosomes uncoil * Cytokinesis * Diploid -> Haploid

Question 33

Describe the process in prophase 2 during meiosis

Answer 33

* The chromosomes, which consist of two chromatids, coil and condense * The nuclear envelope breaks down and spindle fibres formation begins

Question 34

Describe the process in metaphase 2 during meiosis

Answer 34

* The individual chromosomes line up on the equator * Independent assortment * more genetic variation

Question 35

Describe the process in anaphase 2 during meiosis

Answer 35

* The chromatids of the individual chromosomes are pulled to either poles after division of centromere

Question 36

Describe the process in telophase 2 during meiosis

Answer 36

* Chromatids assemble at the poles * The chromosomes uncoil and form chromatin again * The nuclear envelope reform and the nucleolus become visible * Cytokinesis * Four daughter cells formed * reduction division

Question 37

In what stages of meiosis does independent assortment happen?

Answer 37

* Metaphase 1/ 2 * When they line up at the equator the facing of the bivalents/ chromatids are random and independent

Question 38

In what stages of meiosis does crossing over happen?

Answer 38

* Prophase 1 * Chromatids of homologous chromosomes entangled * the regions where they contact are called chiasmata

Question 39

What is bivalent?

Answer 39

When the homologous chromosomes pair up